Adjustable threshold assemblies for doorways are well known in the art and have generally comprised an assembly of an elongated threshold or bar member which is vertically adjustable in an elongated base member and carries a deformable top sealing strip for sealing engagement with the lower edge of a closed door. The base and bar members are commonly formed of thin-walled material, such as aluminum extrudings, with wall thicknesses on the order of 1/16" or so, and the vertical adjustment of the bar member relative to the base member is generally effected by the rotation of adjusting screws which are screw-threaded into threaded openings in a horizontal wall of one of the members and bear against an opposing wall of the other member.
Because of the thin-walled character of the base and bar members of such assemblies, however, it has been found generally necessary, in order to provide a sufficiently supportive screw-threaded engagement or purchase of the adjusting screws with the wall into which they are threaded, to stake or otherwise fasten into the wall a threaded bushing or socket of extended thread length for each of the adjusting screws. Such added bushing members and insertion operations, however, add materially to the number of component parts and to the cost and time required for the manufacture of such assemblies.
Other forms of known adjustable assemblies have employed base or threshold members having either a comparatively thick wall section for the adjusting screws to thread into, or have employed different forms of height adjusting means such as, for instance, cooperating pairs of height-altering wedge members for supporting the threshold bar member which are relatively adjustable longitudinally of the threshold assembly to alter the height of the threshold member. Because of their aforementioned thicker wall construction for the adjusting screws, or their additional components, such other forms of adjustable threshold assemblies are also comparatively costly to manufacture and cumbersome to handle.